Field of the Invention
The present invention relates to a slide motion control apparatus for a mechanical press, and in particular, to a technology that controls a slide of the mechanical press driven by a crank or a link mechanism with respect to a tip portion of a con rod (con rod tip).
Description of the Related Art
Conventionally, as this kind of mechanical press, there have been ones set forth in Japanese Patent Application Laid-Open No. 2011-194466 and Japanese Patent Application Laid-Open No. 2001-062597.
In a press machine set forth in Japanese Patent Application Laid-Open No. 2011-194466, a hydraulic cylinder mechanism is arranged between a tip of a connecting member (con rod) that connects a crankshaft and a slide and the slide, a servomotor for rotating a main shaft of a mechanical press is stopped at a position where the main shaft has been rotated 180 degrees from an upper dead center position, also pressure oil is supplied to the hydraulic cylinder mechanism, and the slide is further pushed down.
Namely, an invention set forth in Japanese Patent Application Laid-Open No. 2011-194466 is a complex type (hybrid type) of press machine that performs press working by mechanical mechanisms, such as a crank mechanism driven by the servomotor, and press working by the hydraulic cylinder mechanism near a bottom dead center of the slide. Particularly, the press machine performs press working by the mechanical mechanism to the position where the main shaft of the press machine has been rotated 180 degrees from the upper dead center position, subsequently, stops the servomotor for rotating the crankshaft, as well as makes the slide operate by the hydraulic cylinder mechanism incorporated between the con rod tip and the slide, and performs so-called “bottoming” or “ramming” working. As a result, deep drawing of a workpiece can be performed, and additionally, the workpiece is slowly press-worked by the hydraulic cylinder mechanism, thereby a crack or the like does not occur in the workpiece, and also springback is prevented from occurring.
A pressure apparatus set forth in Japanese Patent Application Laid-Open No. 2001-062597, a first slider moves to a previously set position by first drive means (a first screw mechanism or crank mechanism), a second slider moves to a predetermined position (fixed point position) by second drive means (a second screw mechanism) that relatively moves to the first slider, and thereby a workpiece existing between the second slider and a substrate is pressed.
In an invention set forth in Japanese Patent Application Laid-Open No. 2001-062597, two drive means of the first drive means that drives the first slider and the second drive means that drives the second slider are used, as the first drive means, means (means with a large pitch in a case of the screw mechanism) is used that can move the first slider to the previously set position (near a fixed point working position) in a short time, and as the second drive means, means (means with a small pitch in a case of the screw mechanism) is used that can accurately position the second slider to a fixed point position, whereby positioning accuracy at the fixed point working position is improved, and also a large pressure force can be obtained.